Overseer Of “Cell”, Mac MPUs Talks Convergence

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SAN JOSE — The man responsible for both the “Cell” processor and the microprocessors powering Apple’s forthcoming Macintoshes preached the gospel of convergence at a keynote address here at the Embedded Processor Forum.

Chekib Akrout, vice-president of PowerPC and networking technology development at IBM, said Tuesday that networking equipment would take on some of the attributes of servers, while servers would take on communications capabilities.

“If you start to look at the application perspective, at the system level, there are the trends between the server and the network, the convergence between the server and the network computer,” Akrout said.

“We see some of the possibilities, like when the server will take on some of the network functions and vice versa, when the network will take care of some of the server functions,” Akrout added.

That wasn’t news to the audience of assembled design engineers and project architects here, who turned out early to hopefully catch a glimpse of either the secretive “Cell” processor, said to be the heart of the Sony PlayStation 3 and related consumer devices, or the next Macintosh. Apple’s Worldwide Developer Conference takes place next week.

However, Akrout’s statements were a reminder that the a processor architecture like the Cell, or the IBM PowerPC, now often does dual duty as both a general-purpose processor as well as a network-optimized computing engine. Akrout joined IBM in 1982, and designed the PowerPC processor used in the Nintendo GameCube as well as processors for the Apple Macintosh. Today, he oversees the Mac microprocessor roadmap.

“You really need to optimize all of these applications on the same base of hardware,” Akrout said.

Analysts said this design trend, more common in the embedded world, is sneaking out into mainstream computing. “I remember when someone asked me about a particular PowerPC processor, and asked if I thought it was going to be in the next Macintosh,” said Tony Massamini, chief of technology for Semico Research. “I said, ‘Well, sure. They’ve had a networking processor based upon it for six months.'”

Embedded designers face the common question: design for a single chip and lose potential flexibility in adding additional I/O capabilities, or design a more expensive menu of several chips designed for specific purposes. Meanwhile, managers are asking designers to turn around a new microarchitecture every two years, or less, Akrout added.

Power must also be considered. In fact, it can often be more important than performance, Akrout said. Sharp-eyed readers at Slashdot noted that the new Fossil Palm-powered wristwatch advertised at Amazon uses the equivalent of a two-hour battery.

“It’s a very important piece,” Akrout said. “I believe if we can’t manage the power well, we’ll never get the performance out of it, because we’ll always be managed by power.” IBM’s strategy has been to design processors that degrade gracefully, scaling power down so as never to stop running the application in question.

But Akrout also added a bit of fuel to the fire surrounding Apple’s potential use of the 64-bit PowerPC 970, which IBM disclosed last October. IBM said then that it expected the chip to run at a double-clocked 450-MHz, or the equivalent of 900-MHz. The 64-bit chip also includes a 64-bit compatibility mode.

“Most of the processors start at 2, 4, 8, and have gone to 16 bits, with 32 bits used by most of us here,” Akrout said. “64 bits has found a space in the server.

“In reality, 64-bits is just coming close to us, more than we can think,” Akrout said. The “idea”, he added, was to produce a 64-bit architecture with 32-bit capability. However, Akrout never mentioned the PowerPC 970 by name.

Finally, Akrout said that IBM “can see in the future” the need for thread-level parallelism, which Intel has branded “hyperthreading”. IBM’s efforts will attempt to convert thread-level parallelism to instruction-level parallelism, he said.

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